public virtual void Add(
	T item
)

public:
virtual void Add(
	T item
)

Parameters

item

Type: T
Item to be added to the collection.

Implements

This method is not abstract, although derived classes should always override it. It is not abstract because some derived classes may wish to reimplement Add with a different return type (typically bool). In C#, this can be accomplished with code like the following:

public class MyCollection<T>: CollectionBase<T>, ICollection<T>
{
    public new bool Add(T item) {
        /* Add the item */
    }

    void ICollection<T>.Add(T item) {
        Add(item);
    }
}

Reference